1. Field
One embodiment of the invention generally relates to a disk drive, and particularly relates to a method for writing data in a disk drive of a perpendicular magnetic recording method.
2. Description of the Related Art
In general, in a disk drive which represents a hard disk drive, a rotary type (rotation type) actuator is used as a mechanism for positioning a head at a targeted position (track of an access object) on a disk medium which is a data recording medium.
In the case where a head mounted on such a rotary type actuator is subjected to positioning control (servo control) in the radial direction on the disk medium by control of a CPU which is a main controller of the drive, a so-called azimuth angle is generated in an inner circumferential area or outer circumferential area of the disk medium.
In a disk drive, the servo control is carried out by reproducing a servo pattern (servo data) recorded on the disk medium by a read head contained in the head. In this case, the azimuth angle becomes larger in, for example, the outer circumferential area on the disk medium, and thus, a detection range (detection sensitivity) by the read head is expanded. Consequently, it is a factor causing the lowering of the preciseness of the head positioning.
In order to solve such a problem, there has been proposed a disk drive in which an interval of servo tracks having a servo pattern recorded therein is made narrower in, for example, an outer circumferential area where an azimuth angle becomes larger (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 6-60573).
Moreover, when an azimuth angle is larger, an effective track width of a data track having user data recorded therein is variable, and thus, there is an influence such that the recording density is lowered and so on. In order to solve the problem, a constitution in which a distance between tracks adjoining in the radial direction on a disk medium is changed has been proposed (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 2002-237142).
As a result of an influence generated by the azimuth angle of the head, a so-called fringe area is generated except for an effective recording area in the data tracks in the case where data is written on the disk medium by a write head. This fringe area is an area where data cannot be normally read out by the read head. Particularly, in a disk drive of a perpendicular magnetic recording method, a single pole type head having the length in the circumferential direction of the track is used as a write head, so that the fringe area is generated in a degree that cannot be neglected due to the azimuth angle.
In the above-described prior-art literatures, the technology capable of solving, particularly, the influence of the fringe area by the azimuth angle has not been proposed.